1,3,5-TRIS-(2-CARBOXYETHYL)ISOCYANURATE CROSSLINKING AGENT FOR POLYEPOXIDE COATINGS

Abstract: Novel curable compositions based on carboxy/epoxy chemistry and cured coatings produced thereby are provided. The curable compositions employ 1,3,5-tris-(2-carboxyethyl)isocyanurate as the polybasic carboxylic acid crosslinker. The crosslinker is combined with a polyepoxide such as those obtained by copolymerizing glycidyl methacrylate with one or more epoxy-free olefinically-unsaturated monomers. The polyepoxide typically has a molecular weight of 1,000 to 30,000, an epoxy equivalent weight of 50 to 5,000, and a glass transition temperature of 10 DEG C to 120 DEG C. A cure catalyst such as triphenyl phosphine may also be used. Heat curing the compositions of the invention produces hard films useful as chip-, scratch- and mar-resistant coatings for automotive applications and as general use coatings for industrial applications.

Description: 1 ,3,5-TRIS-(2-CARBOXYETHYL) ISOCYANURATE CROSSLINKING AGENT FOR POLYEPOXIDE COATINGS BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the preparation of cured polyepoxide coatings using 1 ,3,5- tris-(2-carboxyethyl) isocyanurate as a crosslinking agent. Description of the Related Art Coatings prepared by curing polyepoxides with polybasic acid compounds have been described in European Patent No. 480,120; U.S. Patent Nos. 4,011 ,381 ; 4,346,144; 4,764,430; 4,681 ,81 1 ; 4,650,718; 4,703,101 ; 3,787,521 ; 3,781 ,380; 3,752,870; 3,730,930; and 4,181 ,642, and Japanese Patent Nos. 59-107,742; 61 -087,767; 61 -087,768; and 61- 087,769. Reaction of polyepoxides with polybasic acids are further disclosed in the following references: Khim. Tekhnol., No. 3, pages 36 to 39 (1976); Sin. Fiz.-Khim. Polim., Volume 13, pages 41 to 43 (1974); and Pol. J. Chem. Volume 52, Number 7-8, pages 1487 to 1494 (1978). Coatings prepared by the above-mentioned methods have, in some cases, advantages such as distinctness of image, adhesion and gloss, as disclosed, for example, in the U.S. patents cited above. These coatings, however, suffer from poor solvent resistance and also from poor appearance which is the result of bubbles in the surface of the coating. While introduction of a long chain monocarboxylic acid into the coating may reduce the amount of bubbles popping in the surface of the coating, it also reduces the crosslink density of the coating, thereby reducing the resistance properties of the cured films. Similarly, for example, even though coatings disclosed in European Patent No. 480,120 have the desirable property of scratch resistance, they also have undesirable properties such as poor gloss. They also require high temperatures to cure. It is an object of this invention to provide a low temperature curing composition which produces coatings having exceptional solvent resistance and hardness, and, at the same time, having a good balance of other film and resistance properties such as high gloss, and good humidity and salt spray resistance. Hard coatings are particularly useful as chip-, scratch- and mar- resistant automotive coatings and also as general use industrial coatings. SUMMARY OF THE INVENTION This invention is broadly a curable composition, and particularly a curable composition adapted for use as a powder coating, comprising: (i) 1 ,3,5-tris-(2-carboxyethyl) isocyanurate; (ii) a polyepoxide; and optionally (iii) a cure catalyst. When cured, the novel composition of the invention produces coatings which have exceptional hardness and solvent resistance. The cured coatings of this invention, due to their hardness, have the advantage of being particularly useful as chip-, scratch- and mar-resistant coatings for automotive applications and as general use coatings for industrial applications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The Crosslinker The crosslinking agent used in the curable composition of the invention comprises 1 ,3,5-tris-(2-carboxyethyl) isocyanurate, hereinafter TCI, and is represented by the formula: The crosslinker may be prepared from cyanuric acid and acrylonitrile by the procedure described in U.S. Patent Nos. 3,485,833 and 3,235,553. The Polyepoxide The polyepoxides usable in this invention are compounds which contain at least two epoxy functionalities per each polyepoxide and include monomenc polyepoxides, dimeric polyepoxides, trimeric, tetrameric, and higher oligomeric polyepoxides, and polymeric polyepoxides. Thus, the term "polyepoxide" in the context of this invention refers to an anchor molecule having a plurality of epoxy functionalities, wherein the anchor is any monomeric, dimeric, trimeric, tetrameric, higher oligomer, or polymeric moiety capable of forming chemical bonds with epoxides or epoxyfunctional groups. The polyepoxides usable in this invention may be represented by the formula: wherein A is an n-functional monomeric, oligomeric or polymeric anchor having n-epoxy groups pendently attached thereto; and R\ R 2 and R 3 are the same or different and each is selected from the group consisting of hydrogen, C,-C 4 alky!, C 6 -C 10 aryl, C-.-C., aralkyl, and a mixture thereof; and n is at least 2. The preferred polyepoxides are low molecular weight copolymers of epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, or a mixture thereof, with one or more epoxy-free olefinically-unsatu rated monomers. The epoxy-free olefinically-unsaturated monomer may be selected from the group consisting of acrylic acid esters with alcohols of 1 to 20 carbon atoms, methacrylic acid esters with alcohols of 1 to 20 carbon atoms, hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, acrylic and methacrylic acid, acrylonitrile. methacrylonitrile, acrylamide, methacrylamide, styrene, alpha-methyl styrene, vinyl acetate, vinyl chloride, vinylidene chloride, dialkyl maleates having alkyls of 1 to 20 carbon atoms, dialkyl fumarates having alkyls of 1 to 20 carbon atoms, maleic anhydride, vinyl toluene, and a mixture thereof. The preferred epoxy-free monomer is selected from the group consisting essentially of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, styrene, and a mixture thereof. The copolymerization reaction may be carried out by known methods such as those described in U.S. Patent Nos. 3,787,521 and 4,181 ,642, and in European Patent Nos. 480,120 and 256,369. The preferred molecular weight of the polyepoxide is in the range of from about 1 ,000 to about 30,000. The epoxy equivalent weight is typically from about 50 to about 5,000 and the glass transition temperature (Tg) is from about 10 °C to about +120 °C. Numerous examples of glycidyl methacrylate copolymers, sometimes referred to herein as GMA copolymers, are available commercially and are described further in EXAMPLE 2. The Optional Cure Catalysts The curable compositions of the invention are capable of curing without the aid of a cure catalyst. However, usually a cure catalyst is added to accelerate the cure rate, thereby reducing bake time. The cure catalyst, when present, is selected from the general groups of basic and nucleophilic compounds, and include phosphines, phosphites, amines, oxides, alkoxides, hydroxides, carbonates, carboxylic salts, quaternary salts, and the like. Examples of suitable catalysts include alkyl phosphines such as tri-n-octyl phosphine, aryl phosphines such as triphenyl phosphine, alkyl phosphites such as tri-n-octyl phosphite, tertiary amines such as 1 ,4-diaza(2.2.2)bicyclooctane (DABCO), heterocyclic amines such as N-methyl imidazole and 4-N,N-dimethylaminopyridine, metal oxides such as calcium oxide, alkoxides such as methoxide, ethoxide or tertiary butoxide, metal hydroxides such as sodium or potassium hydroxide, metal carbonates such as sodium or potassium carbonate, carboxylic salts such as sodium acetate, quaternary salts such as triphenylphosphonium bromide, trimethyl benzylammonium chloride, and trimethylbenzylammonium bromide, metal alkoxides, such as sodium methoxide or potassium tertiary butoxide, and a mixture thereof. Triphenylphosphine and DABCO are the preferred cure catalysts. Ratios and Proportions of Ingredients The ratios and proportions of the ingredients in the curable compositions of the invention are dependant primarily on the epoxy equivalent weight of the polyepoxide. When the polyepoxide used contains high epoxy levels, higher levels of the crosslinking agent are required. Usually, higher levels of the cure catalyst are also used to effect rapid cure. Typically, the weight ratio of the polyepoxide to 1 ,3,5-tris-(2-carboxyethyl)isocyanate crosslinking agent is in the range of from about 98:2 to about 60:40, but preferably the ratio is from about 90:10 to about 75:25. e amoun o ca ay , presen , s yp ca y e range o rom a ou . we g percent to about 5.0 weight percent of the total weight of the curable composition. The curable compositions of the invention may also contain additional optional ingredients common to coatings applications such as neutralizing amines, fillers, pigments, adhesion promoters, antiblistering additives, leveling additives, anticrateπng additives, stabilizing alcohols, antioxidants, ultraviolet light absorbers, plasticizers, mar-proofing agents, corrosion inhibitors, pigment wetting additives, or a liquid medium such as water, an organic solvent or a mixture of solvents. Cured Coatings When cured, the novel compositions of the invention form crosslinked films or objects having utility as coatings and as moldings, respectively. The curable compositions of the invention are prepared by admixing the ingredients either to form curable powders for powder coatings applications, or, when a liquid medium is present, to form a curable solution or a suspension or an emulsion for liquid coatings or adhesives applications. The admixture is then applied onto a substrate either, for example, by an electrostatic spraying technique in the case of powders, or it is applied by a technique such as spraying, padding, brushing, rollcoating, curtaincoating, flowcoating, electrocoating or dipping in the case of liquid coatings. The coated substrate is then heated to cure the coating by crosslinking. The unexpectedly superior properties of the curable compositions of the invention include the ability to cure at low temperatures such as 125 °C and the ability to produce films which have exceptionally good hardness such as a Knoop Hardness in the range of 15 to 30, exceptionally good solvent resistance such as an MEK Double Rub of at least 200 without marring, and a good balance of other film and resistance properties such as high gloss, good humidity resistance and salt spray resistance, and good adhesion. Coatings with hardness in the range of 15 to 30 on the Knoop Hardness scale are advantageously usable as chip-, scratch- and mar- resistant automotive coatings and also as "general use" industrial coatings. The following Examples illustrate the various embodiments of the invention. EXAMPLE 1 Preparation of the 1 ,3,5-tris-(2-carboxyethyl)isocyanurate To a 1000 ml round bottom flask was added 64.5 g of isocyanuric acid along with 300 ml of water. A stir bar was added, and then 51 g of triethylamine was charged. The solution was stirred for 30 minutes at room temperature. Then 87 g of acrylonitrile was added to the solution. The solution was heated under reflux for 12 hours. The solution was then cooled to room temperature and the precipitated solid was filtered off. The dried solid weighed 133 g (92%). The melting point was 222-224 °C. To a 500 ml round bottom flask was added 94 g of tris-(2-cyanoethyl) isocyanurate along with 200 ml of a 36% solution of hydrochloric acid. The solution was heated under reflux for 4 hours, filtered through a fritted funnel, and then allowed to cool to room temperature. The crystals obtained weighed 105 g (98%). The melting point was 226-228 °C. EXAMPLE 2 Commercial Polyepoxides Several commercially available polyepoxides were characterized with respect to their molecular weight, equivalent weight, glass transition temperature, and composition. The results are summarized in TABLE 1 . CHARACTERIZATION OF COMMERCIALLY AVAILABLE POLYEPOXIDES COMMERCIAL POLYEPOXIDES Tg (3i (Supplier) Mw° EW 2 (°C) Composition'- Almatex® PD7610 (Mitsui Toatsu) 7000 510 45 G MA/STY/MM A/others' 1 Almatex® PD6100 (Mitsui Toatsu) 12,500 1030 63 GMA/STY/MMA/others (E Estron® GMA-252 (Estron Chemicals) 8300 250 36 GMA/STY/MMA/others (l Blemmer® CP-15 (Nippon Oil & Fat) 12,300 1000 63 GMA/STY/MMA/others' 5 Blemmer® CP-30P (NOF Corporation) 10,300 530 62 GMA/STY/MMA/others (: Blemmer® CP-5SA (NOF Corporation) 10,100 3000 96 GMA/STY/MMA/others (5) (1 ) The molecular weight was determined by High Performance Size Exclusion Chromatography (HPSEC) with reference to sulfur as internal standard. Mw is the weight average molecular weight. (2) The equivalent weight (EW) was supplied by the manufacturer. (3) The glass transition temperature (Tg) was determined by Differential Scanning Caiorimetry (DSC). (4) The composition was determined by 'H Nuclear Magnetic Resonance Spectroscopy (NMR) (5) GMA = Glycidyl Methacrylate STY = Styrene MMA = Methyl Methacrylate EXAMPLE 3 Part A Formulations 1 to 17 were prepared using glycidyl methacrylate (GMA) copolymers. and 1 ,3.5-tris-(2-carboxyethyl)isocyanurate (TCI) crosslinker and a cure catalyst as follows: A 50 weight percent solution of the GMA copolymer, the TCI crosslinker, and the catalyst in N,N-dimethylformamide (DMF) was prepared and applied to Bonderite® 1000 panels using a #32 wire cator applicator. (Bonderite® is a registered trademark of Parker Chemical Company for phosphated cold rolled steel (CRS). "Iron phosphated CRS" is equivalent to "Bonderite 1000".) After drying at room temperature for a few minutes, the coated panels were p ace orzon a y n a mec an ca orce s ream convect on oven at a spec e temperature/time cure cycle. After curing the panels, the physical and resistance properties of the resulting coatings were measured. Part B The procedure in EXAMPLE 3, PART A was repeated with the exception that TCI crosslinker was replaced with dodecanedioic acid (DDA), a commonly used difunctional crosslinking agent. The Formulations obtained in this manner were Formulations 51 to 67. The physical and resistance properties of coatings in the comparative pairs are summarized in TABLES 2 to 18. TABLE 2 COMPARATIVE 1 Formulation (1) 82:18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (51) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (1 ) (51 ) MEK Resistance 200/200 25/200 Pencil Hardness 4H I i — ------ 1 1 Crosshatch Adhesion 5 5 Knoop Hardness 20.6 14.6 Impact Resistance F/R (in-lbs) 20/10 >100/>100 Humidity Resistance (60 °C) very good excellent Salt Spray Resistance good very good Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Almatex® PD7610, copolymer of glycidyl methacrylate. TCI = 1 ,3,5-Tris-(2-carboxyethyl) isocyanurate. DDA = Dodecanedioic acid. Catalyst = triphenylphosphine, based on crosslinker. TABLE 3 COMPARATIVE 2 Formulation (2) 82: 18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (52) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (2) (52) Crosshatch Adhesion 5 5 Knoop Hardness 23.0 16.6 Impact Resistance F/R (in-lbs) 40/10 >100/>100 Humidity Resistance (60 °C) very good excellent Salt Spray Resistance good very good Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Almatex® PD7610, copolymer of glycidyl methacrylate. Catalyst = triphenylphosphine, based on crosslinker. TABLE 4 COMPARATIVE 3 Formulation (3) 69:31 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (53) 69.31 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (3) (53) MEK Resistance 10/200 10/200 Pencil Hardness 5H H-2H Crosshatch Adhesion 5 5 Knoop Hardness 23.1 11.7 Impact Resistance F/R (in -lbs) 50/<10 130/130 Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Estron® GMA-252. Catalyst = triphenylphosphine, based on crosslinker. COMPARATIVE 4 Formulation (4) 90:10 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (54) 90:10 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (4) (54) MEK Resistance 10/200 10/70 Pencil Hardness 4H-5H 2H-3H Crosshatch Adhesion 5 5 Knoop Hardness 17.2 16.4 Impact Resistance F/R (in-lbs) 20/<10 40/<10 Humidity Resistance (60 °C) good (340h) very good (430h) Salt Spray Resistance fair (430h) very good (430h) Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Almatex® PD6100. Catalyst = triphenylphosphine, based on crosslinker. TABLE 6 COMPARATIVE 5 Formulation (5) 90:10 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (55) 90:10 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (5) (55) MEK Resistance 10/190 10/85 Pencil Hardness 4H-5H 2H-3H Crosshatch Adhesion 5 5 Knoop Hardness 18.2 15.7 Impact Resistance F/R (in-lbs) 30/<10 30/<10 Humidity Resistance (60 °C) good (430h) very good (430h) Salt Spray Resistance fair (430h) very good (430h) Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Almatex® PD6100. Catalyst = triphenylphosphine, based on crosslinker. TABLE 7 COMPARATIVE 6 Formulation (6) 90:10 GMA copolymer: crosslinker (TCI)/2% catalyst Formulation (66) 90:10 GMA copolymer: crosslinker (DDA)/2% catalyst Coatings (6) (56) MEK Resistance 1/150 1/90 Pencil Hardness 5H 2H-3H Crosshatch Adhesion 5 5 Knoop Hardness 16.0 12.9 Impact Resistance F/R (in-lbs) 20/10 40/10 Humidity Resistance (60 °C) fair (400h) excellent (400h) Salt Spray Resistance poor (400h) very good (400h) Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Blemmer® CP-15. Catalyst = triphenylphosphine, based on crosslinker. TABLE 8 COMPARATIVE 7 Formulation (7) 90:10 GMA copolymer.crosslinker (TCI)/2% catalyst Formulation (57) 90:10 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (7) (57) MEK Resistance 3/190 3/1 10 Pencil Hardness 4H 3H Crosshatch Adhesion 5 5 Knoop Hardness 17.2 13.7 Impact Resistance F/R (in-lbs) 30/10 70/70 Humidity Resistance (60 °C) fair (440h) excellent (400h) Salt Spray Resistance poor (400h) very good (400h) Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Blemmer® CP-15. Catalyst = triphenylphosphine, based on crosslinker. TABLE 9 COMPARATIVE 8 Formulation (8) 96:4 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (58) 96:4 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (8) (58) MEK Resistance 1/35 1/3 Pencil Hardness 3H-4H 4H-H Crosshatch Adhesion 4 4 Knoop Hardness 18.8 20.0 Impact Resistance F/R (in-lbs) <10/<10 <10/<10 Humidity Resistance (60 °C) good (400h) excellent (400h) Salt Spray Resistance poor (400h) good (400h) Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Blemmer® CP-5SA. Catalyst = triphenylphosphine, based on crosslinker. TABLE 10 COMPARATIVE 9 Formulation (9) 96:4 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (59) 96:4 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (9) (59) MEK Resistance 1/90 1/5 Pencil Hardness 4H-5H 4B-H Crosshatch Adhesion 4 4 Knoop Hardness 27.0 20.0 Impact Resistance F/R (in-lbs) <10/<10 <10/<10 Humidity Resistance (60 °C) good (400h) excellent (400h) Salt Spray Resistance poor (400h) good (400h) Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Blemmer® CP-5SA. Catalyst = triphenylphosphine, based on crosslinker. TABLE 11 COMPARATIVE 10 Formulation (10) 82:18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (60) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (10) (60) MEK Resistance 20/200 20/200 Pencil Hardness 5H 3H-4H Crosshatch Adhesion 5 5 Knoop Hardness 20.1 16.2 Impact Resistance F/R (in-lbs) 30/<10 160/100 Humidity Resistance (60 ' °C) very good (430h) very good (430h) Salt Spray Resistance good (430h) very good (430h) Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Blemmer® CP-30P. Catalyst = triphenylphosphine, based on crosslinker. TABLE 12 COMPARATIVE 11 Formulation (11) 82:18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (61 ) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (11 ) (61) MEK Resistance 20/200 20/200 Pencil Hardness 5H 3H-4H Crosshatch Adhesion 5 5 Knoop Hardness 21.2 16.4 Impact Resistance F/R (in-lbs) 40/<10 160/100 Humidity Resistance (60 ' 3 C) very good (430h) very good (430h) Salt Spray Resistance good (430h) very good (430h) Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Blemmer® CP-30P. Catalyst = triphenylphosphine, based on crosslinker. TABLE 13 COMPARATIVE 12 Formulation (12) 82:18 GMA copoiymeπcrosslinker (TCI)/1 % catalyst Formulation (62) 82:18 GMA copolymeπcrosslinker (DDA)/1% catalyst Coatings (12) (62) MEK Resistance 10/200 30/200 Pencil Hardness 5H H-2H Crosshatch Adhesion 5 5 Knoop Hardness 19.6 13.3 Impact Resistance F/R (in-lbs) 30/<10 120/50 Humidity Resistance (60 °C) good (430h) very good (430h) Salt Spray Resistance fair (340h) very good (430h) Cure Cycle = 20 minutes at 175 °C. GMA copolymer = Almatex® PD 7610. Catalyst = triphenylphosphine, based on total resin solids. TABLE 14 COMPARATIVE 13 Formulation (13) 82:18 GMA copolymeπcrosslinker (TCI)/1% catalyst Formulation (63) 82:18 GMA copolymeπcrosslinker (DDA)/1% catalyst Coatings (13) (63) MEK Resistance 10/200 40/200 Pencil Hardness 5H 2H-3H Crosshatch Adhesion 5 5 Knoop Hardness 19.6 14.0 Impact Resistance F/R (in-lbs) 30/<10 140/70 Humidity Resistance (60 °C) good (430h) very good (430h) Salt Spray Resistance fair (340h) very good (430h) Cure Cycle = 20 minutes at 190 °C. GMA copolymer = Almatex® PD 7610. Catalyst = triphenylphosphine, based on total resin solids. LE 15 COMPARATIVE 14 Formulation (14) 82: 18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (64) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (14) (64) MEK Resistance 1/200 1/25 Pencil Hardness 3H-4H 2B-B Crosshatch Adhesion 3 4 Knoop Hardness 19.1 7.3 Impact Resistance F/R (in -lbs) 10/<10 10/<10 Cure Cycle = 20 minutes at 125 °C. GMA copolymer = Almatex® PD 7610. Catalyst = triphenylphosphine, based on crosslinker. TABLE 16 COMPARATIVE 15 Formulation (15) 82:18 GMA copolymeπcrosslinker (TCI)/2% catalyst Formulation (65) 82:18 GMA copolymeπcrosslinker (DDA)/2% catalyst Coatings (15) (65) MEK Resistance 5/200 5/190 Pencil Hardness 4H-5H 4H-5H Crosshatch Adhesion 5 5 Knoop Hardness 20.1 22.0 Impact Resistance F/R (in -lbs) 20/<10 40/10 Cure Cycle = 20 minutes at 150 °C. GMA copolymer = Almatex® PD 7610. Catalyst = triphenylphosphine, based on crosslinker. TABLE 17 COMPARATIVE 16 Formulation (16) 82:18 GMA copolymeπcrosslinker(TCI) Formulation (66) 82:18 GMA copolymeπcrosslinker(DDA) Coatings (16) (66) MEK Resistance 30/200 5/200 Pencil Hardness 5H 2H Crosshatch Adhesion 5 5 Knoop Hardness 18.8 16.9 Impact Resistance F/R (in -lbs) 40/<10 100/100 Cure Cycle = 20 minutes at 175 °C GMA Copolymer = Almatex® PD 7610 TABLE 18 COMPARATIVE 17 Formulation (17) 82:18 GMA copolymeπcrosslinker(TCI) Formulation (67) 82:18 GMA copolymeπcrosslinker(DDA) Coatings (17) (67) MEK Resistance 90/200 5/200 Pencil Hardness 5H 2H Crosshatch Adhesion 5 5 Knoop Hardness 21.4 14.2 Impact Resistance F/R (in -lbs) 40/<10 30/30 Cure Cycle = 20 minutes at 190 °C GMA Copolymer = Almatex® PD 7610 Although the present invention has been described with reference to certain preferred embodiments, it is apparent that modifications and variations thereof may be made by those skilled in the art without departing from the scope of this invention as defined by the appended claims.

Claims: CLAIMS: 1. A curable composition comprising: (i) 1 ,3,5-tris-(2-carboxyethyl)-isocyanurate; (ii) a polyepoxide derived from the copolymerization of: (a) an epoxy group-containing olefinically-unsaturated monomer, and (b) an epoxy-free olefinically-unsaturated monomer; and optionally (iii) a cure catalyst. 2. The curable composition of claim 1 wherein the epoxy group-containing monomer (a) is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and a mixture thereof. 3. The curable composition of claim 1 wherein the epoxy-free monomer is selected from the group consisting of acrylic acid esters with alcohols of 1 to 20 carbon atoms, methacrylic acid esters with alcohols of 1 to 20 carbon atoms, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, alpha- methyl styrene, vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride, dialkyl maleates having alkyls of 2 to 20 carbon atoms, dialkyl fumarates having alkyls of 1 to 20 carbons atoms, vinyl toluene, and a mixture thereof. 4. The curable composition of claim 1 wherein the polyepoxide has a weight average molecular weight in the range of from 1 ,000 to 30,000; an equivalent weight of from 50 to 5,000; and a glass transition temperature of from 10 °C to 120 °C. 5. The curable composition of claim 1 wherein a cure catalyst is present and is selected from the group consisting of alkyl and aryl phosphines, alkyl and aryl phosphites, tertiary alkyl and aryl amines, heterocyclic amines, alkoxides, metal oxides, metal hydroxides, metal carbonates, metal carboxylates, quaternary ammonium salts, quaternary phosphonium salts, metal alkoxides and a mixture thereof. 6. The curable composition of claim 1 wherein the weight ratio of the polyepoxide to 1 ,3,5-tris-(2-carboxyethyl)isocyanurate is from 98:2 to 60:40. 7. The curable composition of claim 1 wherein a catalyst is present in an amount of from 0.01 weight percent to 5.0 weight percent of the total weight of the curable composition. 8. A curable composition adapted for use as a powder coating, comprising: (i) 1 ,3,5-tris-(2-carboxyethyl)-isocyanurate; (ii) a polyepoxide; and optionally (iii) a cure catalyst. 9. The curable powder coating composition of claim 8, wherein the polyepoxide is represented by the formula: wherein A is an n-functional monomeric, oligomeric or polymeric anchor having n-epoxy groups pendently attached thereto; and R\ R 2 and R 3 are the same or different and each is selected from the group consisting of hydrogen, C,-C„ alkyl, C 6 -C 10 aryl, C 7 -C,, aralkyl, and a mixture thereof; and n is at least 2. 10. The curable powder coating composition of claim 8 wherein the polyepoxide is derived from the copolymerization of: (a) an epoxy-group containing olefinically-unsaturated monomer, and (b) an epoxy-free olefinically-unsaturated monomer. 11. The curable powder coating composition of claim 10 wherein the epoxy group- containing monomer (a) is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and a mixture thereof. 12. The curable powder coating composition of claim 10 wherein the epoxy-free monomer is selected from the group consisting of acrylic acid esters with alcohols of 1 to 20 carbon atoms, methacrylic acid esters with alcohols of 1 to 20 carbon atoms, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, alpha- methyl styrene, vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride, dialkyl maleates having alkyls of 2 to 20 carbon atoms, dialkyl fumarates having alkyls of 1 to 20 carbons atoms, vinyl toluene, and a mixture thereof. 13. The curable powder coating composition of claim 8 wherein the polyepoxide has a weight average molecular weight in the range of from 1 ,000 to 30,000; an equivalent weight of from 50 to 5,000; and a glass transition temperature of from 10 °C to 120 °C. 14. The curable powder coating composition of claim 8 wherein a cure catalyst is present and is selected from the group consisting of alkyl and aryl phosphines, alkyl and aryl phosphites, tertiary alkyl and aryl amines, heterocyclic amines, alkoxides, metal oxides, metal hydroxides, metal carbonates, metal carboxylates, quaternary ammonium salts, quaternary phosphonium salts, metal alkoxides and a mixture thereof. 15. The curable powder composition of claim 8 wherein the weight ratio of the polyepoxide to 1,3,5-tris-(2-carboxyethyl)isocyanurate is from 98:2 to 60:40. 16. The curable composition of claim 8 wherein a catalyst is present in an amount of from 0.01 weight percent to 5.0 weight percent of the total weight of the curable composition. 17. A cured film or object prepared by heat curing the composition of any one of claims 1-16. 18. The cured film or object of claim 17, having a Knoop Hardness in the range of from at least 15 to 30.

Inventors: LEES ROBERT GERALD, ZEZZA CHARLES ANTHONY, LEES, ROBERT, GERALD, ZEZZA, CHARLES, ANTHONY
Applicants: CYTEC TECH CORP, CYTEC TECHNOLOGY CORP.
Application year: 1994
Main classification: C08G59
IPC codes: C08G59, C09D133, C09D163